md5wrapper.cpp

/*
 *	This is part of my wrapper-class to create
 *	a MD5 Hash from a string and a file.
 *
 *	This code is completly free, you
 *	can copy it, modify it, or do
 *	what ever you want with it.
 *
 *	Feb. 2005
 *	Benjamin Grüdelbach
 */

/*
 * Changed unsigned long int types into uint32_t to make this work on 64bit systems.
 * Sep. 5. 2009
 * Petr Mrázek
 */

//----------------------------------------------------------------------
//basic includes
#include <algorithm>
#include <fstream>
#include <iostream>
#include <errno.h>
#include <string.h>
//my includes
#include "md5wrapper.h"
#include "md5.h"

//---------privates--------------------------

/*
 * internal hash function, calling
 * the basic methods from md5.h
 */
std::string md5wrapper::hashit(unsigned char *data, size_t length)
{
	MD5Context ctx;

	//init md5
	MD5Init(&ctx);
	//update with our string
	MD5Update(&ctx, data, length);

	//create the hash
	unsigned char buff[16] = "";
	MD5Final((unsigned char*)buff,&ctx);

	//converte the hash to a string and return it
	return convToString(buff);
}

/*
 * converts the numeric hash to
 * a valid std::string.
 * (based on Jim Howard's code;
 * http://www.codeproject.com/cpp/cmd5.asp)
 */
std::string md5wrapper::convToString(unsigned char *bytes)
{
	char asciihash[33];

	int p = 0;
	for(int i=0; i<16; i++)
	{
		::sprintf(&asciihash[p],"%02x",bytes[i]);
		p += 2;
	}
	asciihash[32] = '\0';
	return std::string(asciihash);
}

//---------publics--------------------------

//constructor
md5wrapper::md5wrapper()
{
}


//destructor
md5wrapper::~md5wrapper()
{
}

/*
 * creates a MD5 hash from
 * "text" and returns it as
 * string
 */
std::string md5wrapper::getHashFromString(std::string text)
{
	return this->hashit((unsigned char*)text.data(), text.length());
}

/*
 * creates a MD5 hash from
 * a file specified in "filename" and
 * returns it as string
 * (based on Ronald L. Rivest's code
 * from RFC1321 "The MD5 Message-Digest Algorithm")
 */
std::string md5wrapper::getHashFromFile(std::string filename, uint32_t & length, char * first_kb)
{
    FILE *file;
    MD5Context context;

    int len;
    int saved = 0;
    unsigned char buffer[1024], digest[16];

    //open file
    if ((file = fopen (filename.c_str(), "rb")) == NULL)
    {
        return "file unreadable.";
    }
    length = 0;
    //init md5
    MD5Init (&context);

    //read the filecontent
    while (1)
    {
        errno = 0;
        len = fread (buffer, 1, 1024, file);
        if(saved < 1024 && first_kb)
        {
            memcpy(first_kb + saved, buffer, std::min (len, 1024 - saved));
            saved += len;
        }
        length += len;
        if(len != 1024)
        {
            int err = ferror(file);
            //FIXME: check errno here.
            if(err)
            {
                fclose(file);
                return strerror(err);
            }
            if(feof(file))
            {
                MD5Update (&context, buffer, len);
                break;
            }
        }
        MD5Update (&context, buffer, len);
    }

    /*
    generate hash, close the file and return the
    hash as std::string
    */
    MD5Final (digest, &context);
    fclose (file);
    return convToString(digest);
 }

/*
 * EOF
 */